The printer has a non-USB connection and must be shared using Devices and Printers in Control Panel.

An incorrect printer driver is installed. Printers must use the correct driver for the type of computer they are connected to (x86-based or x64-based). Many printer drivers can be downloaded automatically from Windows Update. Downloading and installing drivers from Windows Update might take up to 30 minutes. Drivers are also available from the printer manufacturer’s website. For more information, see Find and install printer drivers for Windows 7.

If you still can’t access or print to a printer in your homegroup, there might be a problem
with your network. To run the Network troubleshooter, right-click the network icon (‍‌ or‌ ‍) in the notification area of your taskbar, and then click Troubleshoot problems.

Sometimes, restarting your computer or leaving the homegroup and then rejoining it might help you access printers in the homegroup.